Box filter



FIG. 1 is a side elevational view of a box filter, showing my new design, the opposite side elevational view being identical thereto;

FIG. 2 is a right end elevational view thereof;

FIG. 3 is a left end elevational view thereof;

FIG. 4 is a top plan view thereof, the bottom plan view being identical thereto;

FIG. 5 is a side elevational view of a second embodiment of FIG. 1, the opposite side elevational view being identical thereto;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a left side elevational view thereof; and,

FIG. 8 is a top plan view thereof, the bottom plan view being identical thereto. 

The ornamental design for a box filter, as shown and described. 